We are a long way from the days of exploding cigars. Those were the cigars the CIA schemed to provide to Fidel Castro in the early 1960s as part of its campaign of assassination and sabotage against the Cuban revolution.

Revelations that the CIA had conspired with Mafia figures to kill Castro shocked the nation and led to reforms aimed at preventing officially sanctioned assassination and keeping the CIA within the bounds of the law.

Now the CIA is involved in the targeted killing of individuals by means of drone aircraft, a campaign that is far more menacing than what we know of the slapstick capers in Cuba. It was obvious then that the U.S. government ought not to send Mafia hit men to kill foreign leaders. Now the drone campaign is being waged at the direction of the president on murky legal terrain for the purpose of national security.

Lately, President Obama has authorized the release to members of Congress of secret documents said to form the administration’s legal justification for the drone strikes. Many people have been uneasy about the liberties Obama has allowed himself in targeting people in Pakistan, Yemen and Somalia, sometimes U.S. citizens, who are alleged to be terrorists.

The issue is a legal and ethical minefield. The Bush administration had earned the world’s disdain through the flimsy legal justifications it offered for the torture it was practicing as part of its war on terror. Obama was critical of Bush’s torture policy and its justifications, which were flagrant violations of U.S. and international law.

Now Obama finds himself in the position of justifying something more extreme than torture: the intentional killing of specific people. It is justified as self-defense. Al-Qaida attacked the United States in 2001, and ever since the United States has been waging a war of self-defense against those who attacked us. The war in Afghanistan was justified as a war of self-defense because the Taliban government there had provided safe haven for al-Qaida. As our drones fire rockets at Yemeni rebels in pickups in the Yemeni desert, the killing is construed as part of the same battle.

But is it the same battle, and can we be justified in roaming the world killing at will whatever extremists we perceive as a threat? What is the level of threat that justifies a drone attack? Jihadists in Mali say they are part of al-Qaida, and they are behaving with brutality, threatening stability in West Africa. Conceivably, a band of terrorists in Mali could mount a terrorist strike against the United States, but is that threat imminent enough to warrant targeted killing?

Is instability and insurrection, which are always in progress somewhere in the world, enough of a justification? As far as we know, we have not launched drone strikes in Mali, but is there a reason why we couldn’t?

Obama is said to take the targeting of drone attacks with great seriousness, personally reviewing the list of targets to ensure that U.S. forces are not launching rockets willy-nilly. That is admirable in a leader, but we are a nation of laws. It is important that the policy for ascertaining threats is clear enough that U.S. citizens and the citizens of the world know that America does not believe it can act with impunity to kill whomever it pleases.

Members of Congress have been proceeding with caution on the issue of drones, partly because the program itself has, officially, been a secret and partly because they don’t want to remove a valuable weapon from American hands. But our weapons must be wielded within the strictures of U.S. and international law. The shame of the torture practiced under the Bush administration was that it flouted the canon of decency in the Geneva accords and in U.S. democratic values. Acts of self-defense must not flout those standards of decency.

If our drone strikes are legitimate acts of self-defense, then the Obama administration need not fear discussing its policies. If they are straying into the territory of lawless behavior, then we need to know about it before our policies, like those cigars, blow up in our face.